This invention relates to an artificial airway device designed to facilitate lung ventilation and the insertion of endo-tracheal tubes or related medical instruments into the laryngeal opening of an unconscious patient, and more specifically, to a laryngeal mask device designed to be placed within the oropharynx region over the laryngeal opening, and secured by means of air inflation, thereby sealing the circumference of the laryngeal opening against the aspiration of regurgitated gastric contents and providing a direct pathway from a point exterior to the oral cavity to the laryngeal opening.
In general, laryngeal masks allowing for both rapid lung ventilation and the insertion of medical instruments and tubes into the laryngeal openings of patients have been described in patents such as Brain, U.S. Pat. No. 4,509,514. Consisting of two essential parts, a breathing tube and an inflatable mask, these devices are inserted blindly into a patient's throat, and when properly positioned, terminate at the laryngeal opening. A seal is then formed around the circumference of the laryngeal opening by the inflation of a ring-like structure located on the front of the mask. Inflation of the ring exerts pressure against both the front and rear portions of the oropharynx, securing the device in place such that the laryngeal opening is positioned within a recessed cavity in the mask face. Extending from a point external to the oral cavity, the flexible breathing tube terminates within the recessed cavity, aligned axially with the laryngeal opening. The positioning of the flexible breathing tube allows the passage of small diameter endo-tracheal tubes or related medical instruments into the laryngeal opening, in addition to allowing for lung ventilation.
Current laryngeal masks have several drawbacks in the areas of placement, lung ventilation, and endo-tracheal intubation. For example, during insertion and positioning, the flexible nature of the deflated ring structure and surrounding mask may allow the distal end of the mask to bend back on itself, preventing proper inflation and the formation of a tight seal. Also, once successfully installed, the current mask designs may fail to exert sufficient pressure against the larynx necessary to maintain proper positioning during intubation and ventilation. This is due to the variations in anatomy of the oropharynx region, the muscular tension against which the mask is exerting pressure, and the curvature of the device itself.
During lung ventilation, it is possible for the tip of the epiglottis to become lodged in the distal lumen of the flexible breathing tube, preventing the passage of air or endo-tracheal tubes. This problem is often overcome by the placement of a series of band structures at the entrance to the distal lumen, preventing the epiglottis from entering the breathing tube. However, these band structures severely restrict the size of endo-tracheal tubes and related medical devices which may be passed through the flexible breathing tube. Furthermore, after the insertion of an endo-tracheal tube or related medical device, it often becomes difficult to remove the laryngeal mask from the patient's oropharynx without dislodging or accidentally extracting the endo-tracheal tube or medical device along with the laryngeal mask.
The removable laryngeal mask of the present invention overcomes these problems and is distinguished from the prior art by providing generally the same function as described above yet allowing a more secure and certain insertion, allowing the unrestricted passage of large diameter endo-tracheal tubes directly to the laryngeal opening, and providing alternate airways to prevent blockage of the flexible breathing tube during patient ventilation.